Preparation of bis(2-fluoro-2,2-dinitroethyl)formal



United States Patent 3,541,160 PREPARATION OF BIS(2-FLUORO-2,2- DINITROETHYL)FORMAL Mortimer .I. Kamlet, London, England, assignor to the United States of America as represented by the Secretary of the Navy No Drawing. Filed Dec. 4, 1962, Ser. No. 243,196

Int. Cl. C07c 41/00, 43/12 U.S. Cl. 260--615 7 Claims The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to novel methods of preparing energetic plasticizers for rubbery explosive and propellant compositions. More particularly, it is directed to novel methods of preparing bis(2-fluoro-2,2-dinitroetl1yl)formal. formal.

Previous methods for the preparation of bis(2-fluoro- 2,2-dinitroethyl)formal are not only expensive but are inefiicient due to the high concomitant formation of undesirable side products and tedious, time consuming recovery methods.

It has now been found that bis(2-fluoro-2,2-dinitroethyl)formal may be elficiently and inexpensively prepared by fluorination of the corresponding metal salts of bis(2,2dinitroethyl)formal such as bis(2-alkali metal-2,2- dinitroethyl)formal, such metal salts being the subject matter of copending application Ser. No. 220,944, filed Aug. 29, 1962, now U.S. Pat. No. 3,373,209.

Accordingly, it is an object of this invention to provide novel methods for preparing bis(2-fluoro-2,2-dinitroethyl) formal.

Another object of the invention is the provision of a method for fluorinating bis(2-alkali metal-2,2-dinitroethyl)formals utilizing elemental fluorine.

Another object of the invention is the provision of a method for fluorinating bis(2-alkali metal-2,2-dinitroethyl)formal utilizing perchloryl fluoride.

Fluorination of bis(2-alkali metal-2,2-dinitroethyl) formal according to the invention includes the utilization of elemental fluorine in water and of perchloryl fluoride in methanol-water.

ELEMENTAL FLUORINE METHOD In this embodiment of the invention, a mixture of the bis(2-alkali metal-2,2-dinitroethyl)formal is admixed with a solvent to form a solution or partially dissolved suspension and a mixture of nitrogen and fluorine is bubbled through the admixture of formal and solvent. Bis(2-fluoro- 2,2-dinitroethyl) formal is recovered.

PERCHLORYL FLUORIDE METHOD In this embodiment of the invention, the solution or partially dissolved suspension of bis(2-alkali metal-2,2- dinitroethyl)formal and solvent is treated with gaseous perchloryl fluoride. Bis(2-fluoro-2,2-dinitroethyl)formal is recovered.

STARTING MATERIALS The bis(2-alkali metal-2,2-dinitroethyl)formals fluorinated by the embodiments described above are prepared by:

(1) Admixture of a solution of alkali metal hydroxide in alcohol with a solution of bis(2,2,2-trinitroethyl)formal in hydrogen peroxide, or

(2) Admixture of a solution of bis(2,2,2-trinitroethyl) formal with a slurry of alkali metal hydroperoxide in methanol-water.

The above-described methods of preparation of the starting compounds employed in the methods of this invention are more fully set forth in copending application Ser. No. 220,944, filed Aug. 29, 1962, now U.S. Pat. No. 3,373,209.

Preparation of bis(2,2,2-trinitroethyl)formal is set forth in copending application Ser. No. 173,592, filed Feb. 15, 1962.

The bis(2-fluoro-2,2-dinitroethy1)formal prepared by the methods of this invention is a derivative of bis(2-alkali. metal-2,2-dinitroethyl)formals such as bis(2-sodium-2,2- dinitroethyl)formal, bis(2 potassium 2,2-dinitroethyl) formal and bis(2-lithium-2,Z-dinitroethyl)formal.

GENERAL PROCEDURE Bis(2-alkali metal-2,2-dinitroethyl)formal is admixed with solvent and a mixture of N /F or, in lieu thereof, perchloryl fluoride is bubbled through the resulting solution at a constant temperature. As: the reaction proceeds the solution will be seen to turn from yellow to deep yellow to milky white at end point. The solution is then cooled, extracted and washed.

In the recovery of the bis(2-alkali metal-2,2-dinitroethyl)formal, as in the first section of Example 1, the dimetallic salt precipitate must be kept wet after the first alcohol wash and prior to commencement of the fluorination procedure, with the exception that it may be used dry, with caution, if after the first alcohol Wash the precipitate is placed in water, warmed to dissolve and allowed to reprecipitate upon cooling to ambient temperature. After reprecipitation the solid may be filtered, washed again with methanol and dried at room temperature in a vacuum dessicator. The dry material has an impact sensitivity of 34 cm., 6:0.12.

The fluorination temperature is preferably from about 5 C. to about 25 C. although temperatures ranging downward to the freezing point of the solution may be used. Obviously, however, such lower temperatures would affect the efliciency of the reaction. Higher temperatures may also be used so long as the reaction does not increase to an uncontrollable rate.

The fluorine or perchloryl fluoride input is continued until the color of the reaction mixture changes, evidencing completion at the reaction. When using elemental fluorine, nitrogen or any inert gas is introduced in admixture therewith in concentrations of from about 1:1 to 5:1, N :F Since the perchloryl fluoride reacts more slowly than the elemental fluorine, admixture with nitrogen is unnecessary.

Bulfering agents such as sodium acetate, sodium carbonate and sodium bicarbonate may be utilized to control pH, the end point being preferably about pH 5-6. The buffers may be added to the solution prior to fluorination or incrementally during fluorination.

The following examples illustrate specific embodiments of the invention but it is to be understood that it is not intended that the scope of the invention should be restricted thereby.

EXAMPLE 1 To 30 g. of bis(2,2,2-trinitroethyl} formal in 225 ml. methanol at 0 C. was added 45 mlv cold 30% hydrogen peroxide, followed by the dropwise addition of 36 g. potassium hydroxide in 210 ml. methanol, the temperature being kept below about 10 C. Bis(potassium-2,2-dinitroethyl)formal was formed as a yellow precipitate and was washed three times with ml. portions of methanol (CAUTIONTHE PRECIPITATE SHOULD NOT BE ALLOWED TO BECOME DRY AT THIS POINT).

The methanol wet bis (potassium 2,2 dinitroethyl)- formal was suspended in a solution of 10 g. sodium carbonate in 500 ml. water and the mixture was concentrated, at a temperature of 50 C., to a total volume of 400 ml. Introduction of elemental fluorine admixed with nitrogen in a ratio of 1:3.75 was initiated and the fiuorination was maintained for 100 minutes at a temperature of 23-25 C.,

'the temperature being held constant by means of an ice dried over Drierite and, upon removal of solvent, there was obtained a small amount of bis(2-fluoro-2,2-dinitroethyl)formal as an amber oil.

Obviously many modifications and variations of the present invention are possible in the light of'the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent of the United States is:

1. The method of preparing bis(2-fluoro-2,2-dinitroethyl)formal which comprises admixing the corresponding metal salt of a bis(dinitroethyl)formal with an inert TABLE I.FLUORINATION OF BIS(POTASSIUM-2,2-DINITROETHYL) FORMAL [400 mls. H]

Yield Tern Time N2/Fz Experiment pH control (1,? (min.) ratio Grams Percent 10 gms. N11 00:-.. 5-6 75 3. 75 1 12.05 47.0 10 gms. N11200:..- 23-25 90 3.75/1 14.11 55.0 10 gnlS. NaHCOa 23-25 90 4/1 14.13 55.2

EXAMPLE 5 solvent and contacting the mixture with a fiuorinating To a Well Stirred solution of 17.4 97 8% Sodium agent selected from the group consisting of fluorine and hydroxide in 150 ml. methanol at 10 C. were added 50 Perchloryl fluonde' ml. of 27.5% hydrogen peroxide. Fifty ml. water were The methofl of prepfmng added to thin the slurry and the mixture was cooled to ethynformal Wi compnses adI,mXmg,an aufah metal 5 C. With continued stirring a solution of 30 g. bis(2,2,2- salt of blsmmltioethyniormal wltil diluent and trinitroethyl)formal in 150 ml. methanol was added dropcontactmg the mlxture w,lth a fluormfmng agent selected wise over a 30 minute period. With continued cooling the g group conslstmg of fluonne and Perchloryl mixture was stirred an additional two hours. g i h d f 2 fl A solution of 10 g. sodium bicarbonate in 550 ml. water 6 met o prepfa'nng 'i was then added portionwise as the solution was concenethynforma} i f compnses admlxmg an alkfih metal trated to a total volume of 400 ml., the temperature durof bls(d mltroethyl?formal bufiermg agent ing this step not being allowed to exceed 40 C. The 40 Yvlth an Inert dlluent and mtroducmg a g.as.eous i yellow solution, analyzed spectrophotometrically at this P grqup Eonslstmg of fluonne point, was found to contain 95% of the theoretical amount an Pete Dry uonde Sald P of bis(sodiumagdinitmethyl)formaL The method of clalm 3 wherein the alkali metal Is As in the preceding example, introduction of elemental hthlum' fluorine was initiated and maintained for 80 minutes after The method of 01mm 3 Wherem the alkah metal 15 which time a milky white end point was reached. The Sodlumfiuorination temperature was 810 C. and the fluorine: T method of Claim 3 Wherem the alkall metal 1s nitrogen ratio was 1:3. potasslllmt The product (recovered as in the preceding example) The method of p p ring (2-fl r0- consisted of 15.04 g. of bis(2-fiuoro-2,2-dinitroethyl)- 5Q et yl)formal which comprises admixingabis(alkali metal formal (58.8% of theoretical).

Further examples are illustrated in Table II.

dinitroethyl)formal with an inert solvent, introucing a gaseous fluorinating agent selected from the group con- TABLE II.-FLUORINATION OF BIS(SODIUM-2,2DINITROETHYL)FORMAL l A quantity of product lost by spillage during work-up.

EXAMPLE 9 To 9.7 g. of the methanol-wet fiber cake of bis(2-potassiurn-2,2-dinitroethyl)formal prepared as in paragraph 1 of Example 1 was added 100 ml. methanol and perchloryl fluoride was bubbled through the solution at a temperature of 40 C. Input of perchloryl fluoride was continued slowly overnight with no stirring and there was obtained an orange solution containing a solid. To the orange solution was added 150 ml. water to dissolve the salt and the solution was extracted with ethyl ether and washed sequentially with water, 5% sodium carbonate and 5% potassium chloride. The solution was sisting of fluorine and perchloryl fluoride into the migrture and incrementally adding a bufiering agent to the mixture during said fiuorination.

References Cited UNITED STATES PATENTS 3,291,833 12/1955 Gold et al. 260-615 X LELAND A. SEBASTIAN, Primary Examiner US. Cl. X.R. 149 ss 

1. THE METHOD OF PREPARING BIS(2-FLUORO-2,2-DINITROETHYL)FORMAL WHICH COMPRISES ADMIXING THE CORRESPONDING METAL SALT OF A BIS(DINITROETHYL)FORMAL WITH AN INERT SOLVENT AND CONTACTING THE MIXTURE WITH A FLUORINATING AGENT SELECTED FROM THE GROUP CONSISTING OF FLUORINE AND PERCHLORYL FLUORIDE. 